This invention relates to inlet guards for containers for canisters holding a chemical such as tetraethylorthosilicate (TEOS).
The chemicals used in the fabrication of integrated circuits must have a ultrahigh purity to allow satisfactory process yields. As integrated circuits have decreased in size, there has been a directly proportional increase in the need for maintaining the purity of source chemicals. This is because contaminants are more likely to deleteriously affect the electrical properties of integrated circuits as line spacing and interlayer dielectric thicknesses decrease.
High purity chemicals have been fed to the integrated circuit fabrication process from a variety of volume containers. Representative examples of such containers are described in U.S. Pat. Nos. 5,465,766; 5,562,132; 5,590,695; 5,607,002; and 5,711,354.
High purity chemical container delivery and change out sequences consist of several steps. Each step is important to achieve the required level of removal of liquid vapor and trace moisture. One such step is the liquid drain sequence. During this sequence the canister may be rapidly depressurized through the inlet valve, for instance, and re-pressurized through the outlet weldment and outlet valve. These line drain sequences, which are commonly carried out in chemical delivery systems for chemicals such as TEOS, may result in splashing and/or spraying of the chemical throughout the interior of the canister. The residual liquids in and around the inlet valve become entrained in the flow of gas during the rapid depressurization step. Each line drain moves more liquid further into the inlet or dry side weldment. For standard materials, and even more so for new materials, multiple line drains are required to adequately remove all liquid from wetted surfaces of valves and tubing.
For standard CVD materials, such as TEOS, TEB, or TEPO, this is typically not a major concern. However, for low vapor pressure and more viscous materials, removal of the liquid in the inlet become increasingly more difficult and more important. These materials are also more reactive and sometimes toxic. These materials must be removed completely for a successful canister change procedure. A solution to this problem, accordingly, would be highly desirable.
The present invention provides a solution to one or more of the problems and/or disadvantages discussed above.
In a first respect this invention is a container, comprising: a cylindrical, hollow body capped on both ends by a base and a top; a conduit that intersects the top and extends into the interior of the container; and a perforated housing that encompasses the portion of the conduit that extends into the interior of the container. In certain embodiments, the conduit may pass through the lid such that the conduit extends through the lid. Likewise, the housing may optionally be integral with the lid. The container may be configured so that the conduit extends out from the top away from the interior of the canister, and wherein a coupler is attached to the conduit above the top. The container may include a level sensor attached to the top that extends into the interior of the canister. The housing may include drainage holes on the lower portion of the housing. The container, conduit, and housing may be made of stainless steel. The container may further comprise an inlet valve that is attached to the conduit. The container may include a portion through which the conduit intersects and transverses the top of a cap seated on the canister for the level sensor. The container may include a digital, float level sensor attached to the top that extends into the interior of the canister. The tip of conduit may extend into the canister and a base of the housing are each at an angle relative to the top of the canister. The conduit may be fitted with a gasket or particle filter to restrict flow through the conduit.
In another broad respect, this invention is a removable splash guard, comprising: a housing having a top and bottom that define an internal space; a lower tube that bisects the bottom, wherein the lower tube has an upper portion which is angled; an upper tube that bisects the top, wherein a portion of the second tube that extends into the internal space contains at least one hole; and a partition interposed between the upper and lower tubes that serves to block movement of a chemical from the lower tube to the opening at the inboard end of the upper tube.
In another broad aspect, this invention is a method for depressurizing a canister that contains a chemical, comprising: attaching a splash guard to a line that runs to the canister; attaching a second line that connects the splash guard to a vacuum source; subjecting the canister to a vacuum; depressurizing the canister by introducing a gas into the canister; wherein the splash guard comprises: a housing having a top and bottom that define an internal space; a lower tube that bisects the bottom, wherein the tube has an upper portion which is angled; an upper tube that bisects the top, wherein a portion of the upper tube that extends into the internal space contains at least one hole; and a partition interposed between the upper and lower tubes that serves to block movement of a chemical from the lower tube to the opening at the inboard end of the upper tube.
In yet another broad respect, this invention is a method for the production of an integrated chip, comprising: providing a chemical to a process tool that employs the chemical in the manufacture of the integrated circuit, wherein the chemical is provided by a canister that is connected to a splash guard comprising: a housing having a top and bottom that define an internal space; a lower tube that bisects the bottom, wherein the lower tube has a upper portion which is angled; an upper tube that bisects the top, wherein a portion of the upper tube that extends into the internal space contains at least one hole; and a partition interposed between the upper and lower tubes that serves to block movement of a chemical from the lower tube to the opening at the inboard end of the upper tube.